1. Field of the Invention
This invention relates to film viewers. More particularly, the invention relates to hand held film viewers capable of accommodating various sizes of film without disassembly of the viewer or time consuming modifications to the viewer. Additionally, the invention relates to hand held film viewers permitting simultaneous viewing of two films.
2. Description of the Prior Art
Today, there is a great need for new and useful instructional aids, especially job performance aids. Specifically, the education community in concert with industry is constantly seeking means to economically and effectively train large numbers of personnel in the shortest possible time. Books are, of course, traditional teaching aids. However, it has been discovered that reading and comprehension skills of personnel do not keep pace with the advancing sophistication of equipment. Therefore, more training and new techniques are required as equipment becomes more complex to use and maintain.
Accordingly, trainers/instructors have investigated the increasing use of films as a teaching aid. However, the viewing of films, particularly film strips, have generally required the use of large, cumbersome projectors requiring a stable surface on which to place the film projector and a screen on which to project the image. Obviously, such projectors have no effective utility outside the classroom. One simply cannot take a film projector to the top of a telephone pole, or under a vehicle.
More recently, film viewers have been developed which permit the viewing of film through a lens contained in the film viewer; however, these film viewers generally have been large and required a surface on which to place the viewer for use. While some of the latter film viewers have been portable to the extent that they are contained in briefcases or other reasonably convenient carrying cases, their size provides only limited convenience, and they have been relatively expensive. Accordingly, such viewers have little utility in providing on-the-job instruction.
In addition to cumbersome size and high cost, existing film viewers have generally provided limited versatility. While some film strip viewers provide a capability for accommodating a particular size of film strip in addition to slides, these viewers are limited to one size of film strip and require significant adjustment or modification of the viewer to accommodate slides.
Frequently, for purposes of educational presentation, it is desirable to view two films simultaneously. Examples, include, but are not limited to, overview/closeup, picture/explanation comparisons, and branching. While the learner progresses with the primary program, the distinct advantage is that the secondary program frame may remain in view or be advanced accordingly. This requirement also frequently is encountered when it is necessary to compare two films such as comparing a master to a copy or comparing an original to a revised version of a film. Existing film viewers do not provide such capability.
The present invention provides a film viewer which permits quick and easy changing from one size film to another without significant adjustment of the viewer or disassembly of the viewer. In particular, the present invention provides for the viewing of various size film strips which may be easily installed for sliding movement between a light source and a lens. Additionally, the present invention provides a simple means for viewing two films simultaneously by exchanging a single channel guide for a dual channel guide. Furthermore, the film viewer of the instant invention is compact and capable of being hand held while in use.